1. Field of the Invention
The present invention relates generally to the field of wireless communications. More specifically, the present invention relates to quantifying idle radio spectrum access across a geographic region.
2. Background Art
IEEE 802.11-compatible wireless devices utilize unlicensed bands of radio spectrum. As such, these devices are popular because they relieve the user of the administrative burden associated with gaining a formal assignment of radio spectrum. However, as these unlicensed wireless devices proliferate, many regions have encountered significant congestion within the unlicensed bands of radio spectrum. This congestion stands in stark contrast with numerous long-term surveys of radio spectrum utilization, which indicate that many licensed bands of radio spectrum exhibit a very low level of utilization, even though fully assigned in a legal sense (see “Comments on NPRM,” Shared Spectrum Inc., ET Docket No. 04-186, November 2004, incorporated herein by reference in its entirety). The present low level of utilization is partially a consequence of long-standing regulations that aim to prevent harmful interference among certain wireless services. Those long-standing regulations implicitly incorporate the limitations of decades-old technologies.
Conventional wireless technologies, such as conventional wireless devices operating within pre-planned or ad hoc wireless communication systems, access multidimensional radio spectrum through a set of specified radio spectrum access parameters. In the case of preplanned wireless systems, the radio spectrum access parameters are obtained from detailed radio enginnering planning tools and the detailed site surveys of existing radio spectrum access across a coverage area. However, the intrinsically unplanned nature of ad hoc wireless systems severely limits the applicability of the detailed radio engineering planning tools and detailed site surveys that are used to configure pre-planned wireless networks. Thus, the configuration of ad hoc wireless networks may not accurately reflect existing radio spectrum conditions across the coverage area.
Conventional wireless devices generally lack the ability to dynamically adjust their radio spectrum access in accordance with changes in existing radio spectrum conditions. However, recent proceedings of the Federal Communications Commission have demonstrated an interest in considering new methods for dynamic spectrum access, including the dynamic access of idle radio spectrum by devices with sufficient intelligence to modify their behavior in order to avoid harmful interference with licensed wireless systems. Thus, a need exists for wireless systems and methods that not only dynamically access the multidimensional radio spectrum, but that are capable of determining the idle portions of multidimensional radio spectrum access within a particular geographic region.
Prior measurement-based studies of radio spectrum occupancy typically sample an observed power spectral density at a few locations within a specified geographic region (see “Comments on NPRM,” Shared Spectrum Inc., ET Docket No. 04-186, November 2004, incorporated herein by reference in its entirety). The applicability of these studies is, however, severely limited by the relatively small sampling of locations across the geographic region.
Additional studies of radio spectrum capacity have recognized the need for larger samples of geo-referenced locations. These studies generally combine larger samples of geo-referenced observation locations with engineering judgments about conventional wireless devices to draw conclusions about spectrum availability (see, for example, “Comments on NPRM,” Motorola, ET Docket No. 04-186, November 2004, incorporated herein by reference in its entirety). Unfortunately, the coupling of the radio spectrum capacity analysis with device-specific technical details limits the relevance of these studies. As such, it is difficult to apply the results from these studies to the problem of assessing the value of emerging wireless devices that dynamically access the multidimensional radio spectrum using agile waveforms.
A need thus exists for methods and systems that are capable of assessing the idle multidimensional radio spectrum across a geographic region of interest. These methods and systems must decouple the multidimensional nature of radio spectrum from its use by existing wireless technologies. Further, these methods and system must base their assessment of the idle multidimensional radio spectrum access on a large-scale sampling of geo-referenced locations across the geographic region. These methods and systems must additionally quantify idle radio spectrum access not only in terms of contiguous frequency bands or channels, but non-contiguously in terms of frequency, time, polarization, waveform design, spatial orientation, and spatial location.
These novel methods and systems are beneficial to wireless networks composed of conventional wireless devices that access the multidimensional radio spectrum in contiguous bands of frequency and time. When used within such conventional wireless networks, these methods and systems quantify radio spectrum capacity in a manner not available through existing radio engineering planning tools.
These novel methods and systems are especially beneficial to the next generation of dynamic spectrum access systems that are capable of accessing the multidimensional radio spectrum using “agile” waveforms. These novel methods and systems generate both contiguous and non-contiguous representations of the idle multidimensional radio spectrum access across a geographic region. Thus, they capitalize upon the ability of emerging technologies to dynamically access the multidimensional radio spectrum in terms of non-contiguous blocks of frequency, time, polarization, waveform design, spatial orientation, and spatial location.